Senior Application Security Engineer

Brex is the intelligent finance platform that enables companies to spend smarter and move faster in more than 200 markets. As a Senior Application Security Engineer, you will focus on identifying and responding to security vulnerabilities across the Brex platform, performing code and design reviews, and conducting penetration testing.

Responsibilities:

• Identifying vulnerabilities, demonstrating business impact, and articulating the risk of specific vulnerabilities to drive prioritization efforts
• Perform penetration testing and design reviews, looking for vulnerabilities and insecure designs, work with engineering and product to design secure product features
• Maintain and build internal tools to automate security efforts, perform SAST and DAST testing of the Brex platform, and support secure development practices
• Build and contribute to a culture of collaborative security excellence through technical leadership, learning sessions, and mentorship within the team and wider organization

Requirements:

• 5+ years work experience in an Application Security or related role
• Ability to find vulnerabilities in complex systems, demonstrating business impact through custom attack chains
• Experience with a wide range of secure development activities including— threat modeling, developer education, and incident response
• Knowledge of Python, scripting languages, and AI/agentic workflows to automate tasks, build tools and improve productivity
• Collaborative mindset paired with strong written and verbal communication skills
• Proficiency with Kotlin, gRPC, GraphQL, Kubernetes
• Previous experience as a software engineer
• Consultancy experience performing web application security reviews
• Experience with securing distributed systems in AWS and cloud environments
• Experience with pentesting and securing agentic features and systems
• Contributions to the wider technical community— open source, public research, mentorship, community organizing, blogging, CVEs, presentations, etc
• Experience submitting to bug bounty programs or responsible disclosure programs